Clinical, neuroimaging, and nerve conduction characteristics of spontaneous Conus Medullaris infarction.

Spontaneous conus medullaris infarction is a rare disease. We describe two patients with spontaneous conus medullaris infarction presenting as acute cauda equina syndrome and their unique electromyography (EMG) findings. Two patients developed acute low back pain with mild asymmetric paraparesis, loss of perianal sensation and sphincter dysfunction. Ankle deep tendon reflexes were reduced in bilaterally. Neither patient had cardiovascular risk factors. Magnetic Resonance imaging showed infarction in the conus medullaris. Functional recovery was good in both patients, but progressive asymmetric calf wasting and sphincter dysfunction remained. EMG studies at follow-up of at least 3 years demonstrate active denervation at the muscles innervated by the first sacrum anterior horn cells. Spontaneous conus medullaris infarction can occur in healthy individuals and presents as cauda equina syndrome. Findings of needle EMG studies indicate a progressive course of sacrum anterior horn cell disorder during long-term follow-up.